class Sass::Engine

def parse_mixin_definition(line)
  mixin_name = line[1..-1]
  @mixins[mixin_name] =  []
  index = @line
  line, tabs = @lines[index]
  while !line.nil? && tabs > 0
    child, index = build_tree(index)
    validate_and_append_child(@mixins[mixin_name], child)
    line, tabs = @lines[index]
  end
  :mixin
end